Most computers and other high speed electronic equipment, which produce significant amounts of electromagnetic radiation, are enclosed within housings designed to contain the EMI emissions. Openings in the housings designed to receive electronic modules, e.g. electro-optic transceivers, provide leakage points for EMI, which must be plugged. Moreover, EMI is also generated by the modules that are plugged into the openings. Accordingly, considerable care must be taken to reduce EMI levels generated at the interfaces between the equipment housing, the electronic modules, and the transmission cables connected thereto.
Various prior art solutions have been proposed to reduce EMI emissions including providing a ring of spring fingers surrounding the openings in the housing for contacting the modules during use, such as those disclosed in U.S. Pat. No. 5,767,999 issued Jun. 16, 1998 to Kayner, and U.S. Pat. No. 6,206,730 issued Mar. 27, 2001 to Avery et al. Alternatively, a module receptacle in the device housing can be provided with spring fingers for contacting the modules when inserted therein, such as the module receptacle disclosed in U.S. Pat. No. 6,416,361 issued Jul. 9, 2002 to Hwang. U.S. Pat. No. 5,766,041 issued Jun. 16, 1998 to Morin et al, U.S. Pat. No. 6,201,704 issued Mar. 13, 2001 to Poplawski et al, U.S. Pat. No. 6,220,878 issued Apr. 24, 2001 issued to Poplawski et al, and U.S. Pat. No. 6,607,308 issued Aug. 19, 2003 to Dair et al disclose optical transceivers including spring clips extending therefrom for contacting module receptacles to reduce EMI emissions.
“Copper” transceiver's are used as short distance patch cables, typically in datacom or telcom equipment rooms, to establish a link between ports in the same room or even in the same cabinet without having to convert to an optical signal and back again to an electrical signal. A multi-conductor electrical cable extends between a pair of copper transceivers, and is soldered at each end thereof directly to the printed circuit board within each of the copper transceivers. Each copper transceiver housing has the size and features of a typical SFP transceiver housing; however, since the electrical cable is permanently fixed within each housing, the typical bail latching mechanism, requiring approximately 90° of rotation is not suitable.
Highly populated module receptacles, such as those disclosed in U.S. Pat. No. 6,878,872 issued Apr. 12, 2005 to Lloyd et al, and U.S. Pat. No. 6,943,287 issued Sep. 13, 2005 to Lloyd et al, include adjacent cage structures which share a common wall. Such tightly packed cage structures make the use of cage mounted spring fingers difficult to mount and align. Moreover, symmetrically-positioned module-mounted spring fingers usually apply equal and opposite forces to a common wall, which can end up deforming one side or the other making one opening too large and the adjacent opening too small. Furthermore, spring fingers, which are made of thin sheet metal, can become bent out of position making them ineffective or an obstruction during insertion.
An object of the present invention is to overcome the shortcomings of the prior art by providing an electronic module with solid EMI shielding projections, including one extending from each side of the module, which are vertically offset from one another.